The invention relates to turbines or compressors for turbine engines, in particular for aeroengines or for industrial turbines.
Improving the performance of turbine engines and reducing their polluting emissions leads to ever-higher operating temperatures being envisaged.
For hot portion elements of turbine engines, proposals have thus been made to use ceramic matrix (CMC) materials. These materials possess remarkable thermostructural properties, i.e. mechanical properties that make them suitable for constituting structural elements together with the capacity for conserving these properties at high temperatures. Furthermore, CMC materials present density that is well below that of the metal materials conventionally used for hot portion elements of turbine engines.
Thus, Documents WO 2010/061140, WO 2010/116066, and WO 2011/080443 describe making rotor wheel blades for turbine engines out of CMC, which blades have incorporated inner and outer platforms.
The use of CMC materials for turbine nozzles has also been proposed in particular in Document WO 2010/146288. That document describes making multi-airfoil or single-airfoil nozzle sectors out of CMC by densifying a fiber preform obtained by shaping a woven blank, the sectors subsequently being juxtaposed to build up a complete nozzle.
A turbine nozzle or a compressor diffuser made in conventional manner out of metal is built up from a plurality of guide vane sectors that are assembled together, each sector comprising an inner platform, an outer platform, and a plurality of airfoils extending between the inner and outer platforms and secured thereto. The inner and outer platforms define the gas or air flow passage through the nozzle or the diffuser. On the outside, the outer platforms of the sectors are secured to tabs enabling the nozzle or the diffuser to be mounted in a casing.